Kotlin Android Countup

countup.kt

private fun stopCountUp(){
        //txtTimer.text = duration.toString()
        val t = Toast.makeText(this,"Stopping countup",Toast.LENGTH_SHORT).show()
        timer2.cancel()
        timer2IsRunning=false
    }

private fun startCountUp(){
    timer2 = object : CountUpTimer(duration.toLong()) {
        override fun onTick(second: Int) {
            txtTimer2.text = second.toString()
        }
        override fun onFinish() {
            txtTimer2.text = (duration/1000).toString()
            timer2IsRunning=false
        }
    }
    timer2.start()
    timer2IsRunning=true
}

CountUpTimer.kt

import android.os.CountDownTimer


abstract class CountUpTimer protected constructor(private val duration: Long) :
    CountDownTimer(duration, INTERVAL_MS) {
    abstract fun onTick(second: Int)
    override fun onTick(msUntilFinished: Long) {
        val second = ((duration - msUntilFinished) / 1000).toInt()
        onTick(second)
    }

    override fun onFinish() {
        onTick(duration / 1000)
    }

    companion object {
        private const val INTERVAL_MS: Long = 1000
    }

}